Final answer:
In many software applications, the shortcut for repeating the last action is Ctrl + Y or F4. This varies, however, with Adobe Photoshop using Ctrl + Alt + Z (Windows) or Cmd + Option + Z (macOS).
Step-by-step explanation:
The shortcut for repeating the last action you made often depends on the software you are using. For example, in Microsoft Word and other Office applications, you can repeat the last action by pressing the keyboard shortcut Ctrl + Y or F4. Similarly, in Adobe Photoshop, the shortcut is Ctrl + Alt + Z on Windows or Cmd + Option + Z on macOS to step forward which can repeat certain actions. This function can be incredibly useful for tasks such as formatting, drawing, or even coding where the same action needs to be applied multiple times.